Not literal but not a joke, it is a serious phrase of figurative speech. It originates from a french revolutionary "When the people shall have nothing more to eat, they will eat the rich.” which is most likely a reference to the famous quote by the same author, ‘At length I remembered the last resort of a great princess who, when told that the peasants had no bread, replied: "Then let them eat brioches.’
— Jean-Jacques Rousseau
The rich said let them eat cake, I propose we eat the rich
I don’t think it’s joking about cannibalism so much as it’s a metaphor or figurative speech.
Although I don’t want some weird prion disease, if rich people were the only remaining food source, I’d eat them.
Suffice it to say, it’s insincere about the cannibalism. The animosity toward billionaires is completely serious.
Not literal but not a joke, it is a serious phrase of figurative speech. It originates from a french revolutionary "When the people shall have nothing more to eat, they will eat the rich.” which is most likely a reference to the famous quote by the same author, ‘At length I remembered the last resort of a great princess who, when told that the peasants had no bread, replied: "Then let them eat brioches.’ — Jean-Jacques Rousseau
The rich said let them eat cake, I propose we eat the rich